Asthma is a long-term inflammatory disease of the airways of the lungs.[3] It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms.[9][10] Symptoms include episodes of wheezing, coughing, chest tightness, and shortness of breath.[2] These may occur a few times a day or a few times per week.[3] Depending on the person, asthma symptoms may become worse at night or with exercise.[3]

Peak flow meters are used to measure the peak expiratory flow rate, important in both monitoring and diagnosing asthma.[1]
SymptomsRecurring episodes of wheezing, coughing, chest tightness, shortness of breath[2]
ComplicationsGastroesophageal reflux disease (GERD), sinusitis, obstructive sleep apnea
Usual onsetChildhood
DurationLong term[3]
CausesGenetic and environmental factors[4]
Risk factorsAir pollution, allergens[3]
Diagnostic methodBased on symptoms, response to therapy, spirometry[5]
TreatmentAvoiding triggers, inhaled corticosteroids, salbutamol[6][7]
Frequencyapprox. 262 million (2019)[8]
Deathsapprox. 461,000 (2019)[8]

Asthma is thought to be caused by a combination of genetic and environmental factors.[4] Environmental factors include exposure to air pollution and allergens.[3] Other potential triggers include medications such as aspirin and beta blockers.[3] Diagnosis is usually based on the pattern of symptoms, response to therapy over time, and spirometry lung function testing.[5] Asthma is classified according to the frequency of symptoms, forced expiratory volume in one second (FEV1), and peak expiratory flow rate.[11] It may also be classified as atopic or non-atopic, where atopy refers to a predisposition toward developing a type 1 hypersensitivity reaction.[12][13]

There is no known cure for asthma, but it is easily treatable.[3] Symptoms can be prevented by avoiding triggers, such as allergens and respiratory irritants, and suppressed with the use of inhaled corticosteroids.[6][14] Long-acting beta agonists (LABA) or antileukotriene agents may be used in addition to inhaled corticosteroids if asthma symptoms remain uncontrolled.[15][16] Treatment of rapidly worsening symptoms is usually with an inhaled short-acting beta-2 agonist such as salbutamol and corticosteroids taken by mouth.[7] In very severe cases, intravenous corticosteroids, magnesium sulfate, and hospitalization may be required.[17]

In 2019 asthma affected approximately 262 million people and caused approximately 461,000 deaths.[8] Most of the deaths occurred in the developing world.[3] Asthma often begins in childhood,[3] and the rates have increased significantly since the 1960s.[18] Asthma was recognized as early as Ancient Egypt.[19] The word "asthma" is from the Greek ἅσθμα, ásthma, which means "panting".[20]